1. Field of the Invention
This invention relates to a disposable blood collection device employing a needle which is retracted within a barrel for shipment prior to use, extended for use, and retracted to a permanently locked position within the barrel to protect against accidental needle sticks after the needle has been used. More particularly, it relates to an improved locking system to hold the needle within the barrel during shipping, securely in the locked position.
2. Background Discussion
Medical devices using needles which are retained in a retracted position after the needle is used to guard against accidental sticks are well known. Such devices are shown, for example, in U.S. Pat. No. 4,650,468; 4,675,005; 4,692,156; and 4,507,117. Devices shown in the aforementioned patents are generally of the hypodermic syringe type, that is, a single needle point normally fixed to the end of a barrel and covered by a protective guard is utilized to inject fluids into or extract fluids from the human body. The needle point is retracted into the syringe barrel and retained therein by various means after use.
A somewhat different type of device has come into use with respect to the collection of blood samples. The device includes a double-ended cannula or needle, again is fixed to one end of the barrel and covered by a protective guard prior to use. The guard is removed and the end of the needle so uncovered is inserted into the patient's vein. A sterile evacuated container is applied to the other end within the barrel so that the pressure differential resulting thereby causes blood to be drawn from the vein into the evacuated container. When the container is filled, it is removed from the needle, thereby providing a sealed blood sample in the container. Examples of this type of device are shown in FIGS. 4-6 of U.S. Pat. No. 4,592,744 and in FIGS. 1-3 of U.S. Pat. No. 4,643,199. In each of these devices, a double-ended cannula is normally fixed to the end of the barrel so that one end extends from the barrel and is covered by a protective guard prior to use. After use, the double ended cannula is retracted within the barrel so as to be disposable without the danger of sticking personnel thereafter handling it. However, both of these devices require the user to use both hands in order to retract the needle after use, and thus are relative complicated and time consuming in use. In addition, having the patient-inserted end of the cannula normally fixed to the end of the barrel takes up additional shipping space and requires removal of the guard prior to use.